The sugarcane plant (Saccharum officinarum) is primarily cultivated for sugar production. However, the sugarcane plant is a tall, leafy, perennial tropical grass that outyields most tropical grasses and that can be a valuable fodder for livestock. As a forage plant, sugarcane has multiple advantages. Sugarcane forage remains available during the dry season and can also be kept as standover in the field during 18 to 20 months without losing its nutritive value, an exception among tropical grasses (Preston, 1988).

All kinds of sugarcane plants are potentially valuable for animal feeding. However, among sugarcane varieties, some have a very high fibre content and this coud result in very variable nutritive value for livestock. It has thus been recommended to choose varieties with lower fibre content for feeding puposes (Pate et al., 2002). Forage sugarcane varieties have been especially bred for forage production (Sakaigaichi et al., 2013).

Morphology

The sugarcane plant is a tufted perennial grass that grows to a height of 2-5 m. The stalks are 2-6 cm in diameter. Sugarcane is a ratooning species and a plant can have 10-15 stems. Sugarcane is leafy. Its leaves are alternate, linear, up to 1-2 m long and 3-8 cm wide, with a very thick midrib. The roots can grow to 6 m depth. There root system is also very well developped in the upper soil layer. The inflorescence is a plumelike panicle, 2-60 cm long. The spikelets are 3 mm long and the seeds are small (1.5 mm) caryopsis (Kew Science, 2017; Duke, 1983).

Uses

Whole sugarcane may be used as green forage and can provide a valuable dry season fodder. Sugarcane forage can be used in a wide range of ways. Sugarcane stalks may be grazed, cut for cut-and-carry systems or directly chopped in the field for further use in the green form or for silage (see Processes below).

Distribution

The sugarcane plant (Saccharum officinarum) is thought to have originated from Polynesia. It has been widespread throughout South-East Asia by humans and a secondary center of origin is reported in Papua New Guinea and Indonesia (OECD-FAO, 2013). Modern sugarcane varieties (Saccharum spp.) are complex interspecific hybrids resulting from crosses between Saccharum officinarum and Saccharum spontaneum.

Sugarcane plants are cultivated in more than 100 tropical and subtropical countries from 30°N to 30°S. Sugarcane is grown as a commercial crop, primarily in South America (Brazil, Colombia and Argentina), North and Central America (Mexico, the USA, Guatemala and the West Indies), Asia (India, China, Thailand, Japan and Indonesia), Africa (South Africa, Zimbabwe and Egypt), Australia and the Pacific islands (OECD-FAO, 2013).

Sugarcane can be grown from sea level up to an altitude of 3000 m. Optimal temperatures are 26-33°C for germination and 30-33°C for growth. For maturation, a period with relatively low night temperatures (below 18°C) improves sucrose content. Sugarcane is sensitive to frost but can regrow from the lower buds. It requires high amounts of water, at least 1500 mm annual rainfall and optimally 1800 to 2500 mm. In places where this level is not reached, irrigation is required. Sugarcane grows on a wide range of soils with pH ranging from 5 to 8, provided they are well-drained (Kuntohartono et al., 1996). Sugarcane has some tolerance of salinity. However, it is considered that above 4.4 dS.m-1, sugarcane cultivation is not economically sustainable (OECD-FAO, 2013). In heavy soils, sugarcane should be grown on raised beds. Sugarcane can withstand short periods of flooding or dought. However, drought causes sucrose loss and when they the canes are reaching maturity flooding causes lodging. Sugarcane is resistant to fire. It is a full sunlight plant (FAO, 2017; Kuntohartono et al., 1996).

Processes

Chopped sugarcane

Sugarcane is better chopped for feeding. Chopping can be done no later than 3 days after cutting with slowly revolving chaff cutters, high speed disintegrators with knives and beaters or with a forage harvester. There is little effect of processing method on nutritive value, it is however recommended to finely chop the sugarcane that will be offered to small ruminants (Archimède et al., 2008; Preston, 1988). However, it should be noticed that fine chopping increases sugar losses and risks of fermentation (Guerra, 2011).

Chopping can be done manually or mechanically as shown in the video below:

The following video shows an example of electric-powered chaff cutter processing sugarcane stalks:

The cane should be fed to animals with no delay after chopping (the same day) as the sugar readily ferments and decreases sugarcane feeding value (Archimède et al., 2008; Preston, 1988).

Derinded sugarcane

In the early 1970s, derinded sugarcane (also called sugarcane pith) was assessed in animal feeding as it was thought that the removal of fibre could increase its nutritive value. However, it was not commercially viable and whole chopped sugarcane was reported to have almost the same nutritive value at much lower cost (Preston, 1988).

Sugarcane preservation

Once chopped, sugarcane can be dried or ensiled so that the feed remains available year-round.

Chemical treatment

Sugarcane could be added calcium oxide at 0.5%, 1% or 2% in order to enhance digestion parameters. This treatment resulted in an increased in situ degradability of DM and OM (Campos et al., 2011).

Drying

A sugarcane that has been previously chopped can be dried (sun-dried or oven-dried). Sun-drying is done by spreading the chopped sugarcane on a plastic sheet in a thin layer (no more than 4 cm) and letting it dry during the day under the sun and mixing it 2-3 times a day. At night, the chopped material should be removed and kept indoor. Drying should be continued until the material is dry enough (Archimède et al., 2008).

Ensiling

Another way of preserving sugarcane stalks is to ensile chopped sugarcane. However, because of its high proportion of the soluble sugars, sugarcane fermentation is prone to be alcoholic, and nutritive value could be subsequently seriously depressed (Alvarez et al., 1977 cited by Preston, 1988).

To prevent such issues, it has been recommended to ensile sugarcane as soon as it is chopped. Baling and wrapping in plastic sheets is a good option (Suzuki et al., 2014).

The video below is an example of modern baling material for sugarcane silage, in Martinique (French West Indies):

The use of additives for sugarcane silage production was also advised.

There is a huge diversity in farm scales worldwide. In some places such as India, China or Vietman, most sugarcane is produced on only 0.3-1 ha land, while, in Australia, the average size of sugarcane farms is between 40 and 250 ha (OECD-FAO, 2013).

Establishment and cultivation

Under rainfed conditions, sugarcane can be planted at the onset of the rainy season or at its end. Irrigated sugarcane is planted at the beginning of the dry season. Sugarcane is generally vegetatively propagated by cuttings of mature stalks that are laid horizontally in furrows previously disk-ploughed to a depth of 30-40 cm. The cuttings are then covered by a thin layer of soil. Cuttings should be planted at 1.1 to 1.3 m intervals when they are manually cultivated, and at 1.45 m in mechanical cultivation. Cuttings start tillering within 1.5-3 months after planting. The number of tillers will increase till the canopy closes. After this stage, they will only elongate in order to get more light. This is also the time of leaf production. Under favourable conditions time lapse between 2 leaves is 5-7 days. The growing period lasts 6-8 months. After this, maturation starts and the crop is ready to be harvested between 12 and 18 months depending on cultivation and environmental conditions (climate, soils, etc.) but also on variety (Kuntohartono et al., 1996).

The tillering period starts about 1.5 months after planting and continues for 1.5-3 months, depending on the cane cultivar. Late tillers (suckers) may develop before harvest (at 8-10 months). They are thick and succulent. They especially grow where light can enter freely, e.g. at field edges and in lodged cane. After the cane canopy has closed, fewer tillers will develop and most existing cane stalks elongate further. Their growth is influenced by the production of leaves and consequently of internodes. The time lapse between the formation of subsequent leaves is known as the "plastochrone". Under favourable growing conditions, the plastochrone is 5-7.2 days long and under unfavourable conditions it is 2 or more weeks. The growth period of sugarcane in South-East Asia is 6-8 months and is related to water availability. Sugarcane can be harvested during 6-8 years before being pulled out (Kuntohartono et al., 1996).

Harvest

In very hot climates, for instance in Louisiana, USA, and Indonesia, the crop can be harvested 9 to 12 months after planting or regrowth, while in other cooler regions, such as the highlands of Hawaii and South Africa, it takes 18 to 24 months (Goebel, 2017). When it is used for forage, sugarcane can be cut earlier and several times, harvesting sugarcane at shorter intervals of 6 months allowing more leafy material and fairly high yields (200 t/ha) (Rangnekar, 1988). In Japan, forage sugarcane could be cut after only 4 months of regrowth (Suzuki et al., 2014). However, in the French West Indies, it was recommended to harvest sugarcane for fodder 12 months after plantation in order to make a trade-off between N content that is higher when the plant is young, and biomass yield that increases with maturity as well as sugar content (Archimède et al., 2011).

Harvest is a very heavy and time consuming activity, it can be done manually or with a harvester. A worker can cut between 3 and 5 tonnes of stems a day, while a mechanical harvester can cut up to 60 tonnes of stems an hour (Goebel, 2017).

Once cut, the sugarcane stalks should be fed to animals with no delay. Sugarcane is better chopped for feeding. In Brazil, sugarcane was harvested daily, chopped and offered to animals. In 1983 in the Sao Paulo State in Brazil, 70% of the farms had sugarcane as green stock (Caielli, 1986). However, the daily cut is time-consuming and it could be interesting to process chopped sugarcane into silage (see Processes above) (Valeriano et al., 2009).

Environmental impact

Prevention of N leaching and erosion

In Japan, sugarcane has been grown in order to reduce drainage of water as well as leaching of mineral N in fields receiving excessive manure around intensive livestock farms (Ishikawa et al., 2014). Sugarcane plant protects efficiently the soils against the erosion due to heavy rains and cyclones (Goebel, 2017).

Carbon sequestration

As a perennial C4 species, the sugarcane plant is a potent sink of carbon. One hectare of sugarcane is a permanent sink for about 80 tonnes of this greenhouse gas (Preston, 1995b).

Nutritional aspects

Nutritional attributes

Sugarcane forage has a high energy content and its nutritive value is at its best during dry periods (Archimède et al., 2011). Sugarcane forage has low protein, mineral and vitamin contents. In addition it is a bulky fibrous material.

Because of its low concentration of crude protein and high fibre content, sugarcane forage is a poor quality roughage that must be complemented with protein rich materials for adequate ration management (Guerra, 2011; Archimède et al., 2008; Preston, 1988). However, in situ DM and OM degradabilities of 6 cultivars (at 5% passage rate) of sugarcane were high, ranging from 74.19 to 86.27% for DM and from 68.22 to 85.41%, suggesting a good potential for ruminant feeding (Arantes, 2014). High and low fibre varieties showed no difference in animal performance (Pate et al., 2002). Whether sugarcane stalks are grazed, used as a soiling crop (entire or chopped) or ensiled, they always require supplementation with protein sources.

In Cuba, a product called "Saccharina" containing 14% crude protein and 90% DM was prepared by adding 15 kg urea and 5 kg minerals to every ton of chopped surgarcane and by drying the mixture (Guerra, 2011).

Principles of sugarcane forage supplementation

Because it is unbalanced for protein, minerals and vitamins, sugarcane-based diets always require supplementation. Correct supplementation of sugarcane forage should aim to:

provide sources of protein, glucose precursors and long chain fatty acids able to bypass (or escape) the rumen fermentation so that the available nutrients are balanced according to the needs of production;

obtain feeds and/or chemical substances capable of manipulating rumen fermentation so as to increase propionate relative to other VFAs, and eliminate (or reduce) protozoa in the rumen (Preston, 1988).

Urea and mineral supplementation

Supplementation is often reported to be done with urea (non protein nitrogen, NPN) (Naves et al., 2015a; Naves et al., 2015b). However, some restrictions should be respected as urea has some toxicity. Urea should not be fed at a rate exceeding 2-3% of the concentrate or grain portion of ruminant diets, and should be limited to less than 1% of the total diet. In the French West Indies, it was suggested to have 10 kg urea per ton of fresh sugarcane (Archimède et al., 2008). Additionally, NPN should constitute no more than one-third of the total nitrogen in ruminant diets. Once the decision is made to feed NPN, animals must be slowly adapted to it, and maintained on a consistent dietary NPN content with no significant deviation (Thompson, 2017).

Minerals and vitamins are necessary for the rumen microbes and the physical attributes of a good rumen ecosystem. They could be provided by highly digestible green forages such as sweet potato tops and foliages of forage tree legumes, such as leucaena, at rates of about 600 g DM/100 kg LW (Preston, 1988).

Combination of urea and protein sources

An important point is that the various types of supplements (urea and other protein sources), which act in the rumen as bypass nutrients, interact. Neither urea nor rice polishings were effective when given alone, yet they had a dramatic effect on animal performance when given together (Preston, 1988). To this respect, the use of foliages from tropical legumes such as gliricidia, leucaena, erythrina, pea, sweet potato, mulberry is very interesting as they provide both non protein nitrogen and by-pass protein (Archimède et al., 2008).

Grazing sugarcane

Sugarcane could be grazed only in emergency situations, and then only once per year and in a manner that completely cleans the grazing area within one week (Pate et al., 2002).

Raw or chopped sugarcane

When sugarcane forage is included in ruminant diets it may represent up to 50-60% of the diet (Lascano et al., 2012; Cordeiro et al., 2007). In small-holder tenure, it was suggested to have green stock of sugarcane for the dry season. In the French West Indies, it is suggested to keep 0.04 ha sugarcane/month of dry spell/ha of grassland. For example, a farmer that has 5 ha of grassland in a place where the dry season is 4 month long should have 0.04*5*4 = 0.8 ha of sugarcane (Archimède et al., 2008).

Dairy cows

When sugarcane forage was used as a basal diet (47% dietary level) for dairy cows, protein supplement was obtained through soybean meal + urea at low level (10 g/kg DM), soybean meal + urea at high level (17 g/kg DM), raw soybean, or corn gluten meal. All protein supplements resulted in the same milk yield but soybean meal + urea at low level (control diet) resulted in the highest protein milk yield (Naves et al., 2015a). In an attempt to reduce the use of costly soybean meal, it was shown that dairy cows in the final third of their lactation could be fed on less CP and higher level of NPN through the use of urea, without affecting DM intake, net energy for lactation or total apparent digestibility. Milk protein yield tended to be lower in cows fed on NPN but no differences were found in milk yield or in cow body condition (de Jesus et al., 2012).

On the contrary, in Cuba, where urea provision may be difficult, it was suggested to use cassava or kenaf foliage in order to replace urea in the supplementation of sugarcane forage/star grass based diets for dairy cows. The foliages could replace urea and yielded more milk than urea supplemented diets (García-López et al., 2016). The use of foliage of sweet potato, erythrina, leucaena and mulberry was also recommended in the French West Indies and it was recommended to avoid urea when these foliages were used (Archimède et al., 2008).

In Brazil, high producing dairy cows were fed on fresh sugarcane in an attempt to replace maize silage. Sugarcane forage decreased DM intake and milk yield and was not recommended for animals at production peak (Corrêa et al., 2003). In India, crossbred cows produced 10-12 kg per day, with an average intake of sugarcane of 20.5 kg per day (Rangnekar, 1988).

Growing and fattening cattle

Because of its low fibre digestibility, sugarcane may limit cattle performance and inclusion levels in the diet of growing cattle may be variable, ranging from 20 to 70%.

Post-weaning crossbred heifers were fed on 70% chopped sugarcane and 30% concentrate with increasing levels of CP (13%, 15%, 19% and 22%). Increasing CP level resulted in higher total apparent digestibility of CP. However, health parameters were found to be better at the lower protein content (13%) (Queiroz et al., 2012).

In Brazil, zebu steers receiving 60% sugarcane forage and 40% concentrate had higher gastrointestinal content at slaughter and their carcass was less compact than those of steers fed on maize silage or bread grass (Brachiaria brizantha) (Macitelli et al., 2005).

In Cuba, crossbred Holstein x zebu steers were fed on 73% sugarcane forage molasses-urea (10%) and concentrate (17%). The animals reached 840 g ADG when the concentrate was offered once a day and 950 g when the concentrate was offered twice a day. It was suggested that CP and energy were better utilized when the concentrate was offered twice. It resulted in better feed conversion ratio (9.2 vs. 11) (Rodríguez et al., 2013).

It was shown that cultivars of sugarcane with higher NDF digestibility included at 20 or 40% of the diet could increase DM intake, final body weight and hot carcass yield, and overall profitability in finishing Nellore bulls (Mesquita, 2013).

Sugarcane forage raw or treated with 0.5% or 0.9% lime (CaO) were included at 50% dietary level in lamb (22 kg BW) diets. The remainder of the diet was concentrate. Diets were formulated in order to meet animal maintenance demands and gains of 150 g/day. CaO addition neither altered nutrient intake nor improved animal weight gain. It was concluded that CaO could be used a a preservative treatment of sugarcane as it had no adverse effect on the animal performance provided the sugarcane was fed 24h after CaO addition (Freitas et al., 2008).

Ensiled sugarcane

Untreated sugarcane silage

Comparisons between chemical composition and digestion parameters of fresh and ensiled sugarcane have been made. They have shown that ensiled sugarcane was significantly (P<0.05) different for DM, fibre (NDF, ADF and lignin) and ash content. However, conclusions about OM and DM in sacco digestibilities were unclear, and no consistent difference could be found (Reyes-Gutiérrez et al., 2015). Earlier results had suggested some reduction in the nutritive value of ensiled sugarcane with IVDMD reduced from 66,4% to 55,3% when measured in sacco in sheep rumen (Alcantara et al., 1989). Poorer composition parameters have also been reported for MS (20.9 vs. 27.3% ), NDF (54.95 vs. 42.1%), ADF (43.8% vs. 34.9%) and lignin (7.2% vs. 6.8%) for ensiled and raw sugarcane, respectively (Coan et al., 2002). These results advocated for the treatment of sugarcane silage. In comparison to fresh sugarcane, ensiled untreated sugarcane resulted in lower DM intake in cows receiving 60% sugarcane and 40% concentrate (Andrade et al., 2016).

Treated sugarcane silage

It was reported that among 5 sugarcane silages treated with either urea (0.5%), sodium benzoate (0.1%), Lactobacillus plantarum, or Lactobacillus buchneri, no significant changes were observed in terms of in sacco ruminal degradability obtained in Nelore steers between treated and untreated silage (Schmidt et al., 2007).

In Cuba, sugarcane silage made out of sugarcane and cattle faeces was fed to dairy cattle during periods of scarcity and resulted in higher milk yield than a mixture of fresh sugarcane and urea (Carrasco et al., 2004).

Growing cattle

Sugarcane silage was treated with fibrolytic enzyme (20 g enzyme per day) in order to reduce fibre content and it was then fed to heifers during 25 days at 54.9% of the diet. It was compared to untreated sugarcane silage, to untreated maize silage, and to maize silage treated with the same enzyme at the same level, and included at 65.3% of the diet. NDF digestibility of treated forages was increased as well as time spent eating. However, enzyme supply decreased N absorption and heifers had lower microbial protein synthesis than those fed on maize silage (Gandra et al., 2017).

Pigs

Growing-finishing pigs

In Cuba, in smallholder farms, it was shown that offering hand-cut (3 cm long), unpeeled sugarcane stalks to pigs resulted in a sugarcane consumption of 11 kg/d, the pig chewing 11 kg sugarcane and letting the fibrous part as orts. This amount could sustain a growth rate of 450 g/d provided the pigs could receive protein supplement (200 g/d) in the form of soybean meal, for example (Mederos et al., 2004).

Frequently just before distribution, stalks are peeled by hand or mechanically, a treatment which makes the sugarcane stalk very palatable for rabbits which consider the product like a candy (Kentor, 1990; Preston, 1995a).

Chopped sugarcane may replace up to 40% of a balanced concentrate without alteration of the growth rate or carcass quality (Ramchurn, 1979). Reproductive performances were the same with a ration of peeled sugar stalk, soybean seeds and legume bean forage than with a control ration of a cereal-based concentrate and Guinea grass (Nguyen Quang Suc et al., 1995).

Leaves

Sugarcane leaves may be used as a source of fibre (more than 65% NDF) in rabbit feeding. For example growth rate was the best (19.5 vs. 12-17g/d for other treatments) after distribution ad libitum of a concentrate with maize grain and fresh sugarcane leaves (15.7%, 52.7% and 31.7% of the total DM intake respectively) (Bien-Aimé et al., 1989).